OMAP4: PM: Program correct init voltages for scalable VDDs

By default the system boots up at nominal voltage for every
voltage domain in the system. This patch puts vdd_mpu, vdd_iva
and vdd_core to the correct boot up voltage as per the opp tables
specified. This patch implements this by matching the rate of
the main clock of the voltage domain with the opp table and
picking up the correct voltage.

Signed-off-by: Thara Gopinath <thara@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>